ML20238E322
| ML20238E322 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 07/29/1987 |
| From: | James Anderson BISCO PRODUCTS, INC. |
| To: | Hodge C Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20238E264 | List: |
| References | |
| NUDOCS 8709140275 | |
| Download: ML20238E322 (3) | |
Text
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Apr bisco July 29, 1987 Dr.
C.
Vernon Hodge bisco products, inc.
Reactor Engineer
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- ,,, 6 68 Generic Communications Branch 0 72)298-1200 Division of Operational Events Assessment telex 282482 brand prid Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Dr. Hodge:
I have reviewed the draft issue of the information notice entitled " Gaps in Neutron Absoring Material in High Density Spent Fuel Storage Racks."
There are a number of points which I feel add to the factual accuracy of it's content, as well as minimize speculation or risk of misinterpretation.
I felt the best way to identify the points was to return to you a re-drafted notice, which is enclosed, and comment on the differences in this letter.
As a preamble, I think it is important to consider that the observed gaps at Quad Cities may be unique to that facility and may not be encountered elsewhere.
This premise considers that the high density rack must be considered as a system, with the neutron absorber one component of that system.
As such, the function or failure of the absorber may be as much affected by the rest of the rack as it is limited by its own properties.
There is no doubt that the Quad Cities racks included some manu-facturing deficiencies, as evidenced by the NRC Preliminary Noti-fication PNO-III-82-12, Commonwealth Edison Company (Quad Cities Nuclear Plant) - Bowed Spent Fuel Storage Racks, a copy of which is enclosed.
The fabrication concerns are further amplified in the July 27, 1987 letter from Dr. Krishna Singh, Holtec International to Mr. Conrad McFadden, NRC, a copy also enclosed.
Of specific relevance to the gap situation are references in Dr.
Singh's letter to the issues of fabrication induced weld damage, warpage, uneven clamping loads, tearing during installation and stretching during installation.
While none of Dr. Singh's comments constitute proof that the gap problem is unique to Quad Cities, they do outline numerous conditions, some or all of which are unique to Quad Cities, which could cause or exaserbate the gap phenomenon.
Given the plausibility of the above premise, the following is a section by section reasoning for the differences between the draft notice and my re-drafted copy:
8709140275 870710 DR ADOCK 05000254 g
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1.
Statement of Purpose A general change throughout was made from the term "degrada-tion" wt'.ch implies various degrees of. partial to total failure or disintegration depending on the orientation of_the reader, to the term " gap" which defines the observed condition.
The fuel. rack and absorber are also identified as-a " system" since they are highly interactive and' considerations of rack L
design,'as well as environment, have significant impact on the function of the absorber.
2.
Description of Circumstances The manufacturer of the rack as well as the absorber are identified.- The licensee usually has a contract with the rack manufacturer and not with the absorber supplier, therefore may be unaware of the source.. The identification L.
further alerts the licensee to the possibility of design similarities betwen the Guad Cities rack and his own.
The description of Bornflex is corrected to reflect actual.
Composition.
Nusurtec was added as an additional investigating agency, contracted by CECO for neutron radiography.
The reference to the preliminary status of the NETCO report was taken from the document'itself and is an important con-sideration for the reader.
The gap formation mechanism was also directly taken from the report summary.
The reference to the location of the gaps was ommitted since the table displaying the data in the NETCO Report indicates the gaps occur throughout the upper 2/3rds of the cell, with insufficient data points to conclude that only two peak locations exist.
The reference to the neutron radiograph was added.
The description of the Pt. Beach coupon sample evaluation was re-written for clarity with comment taken directly from the Wisconsin Electric report to the NRC.
I felt the addd-tion'of the statement that no evidence of gaps or breakage existed was germain to this issue, i
3..
Discussion 1
A list of sites using Oat designed and fabricated racks is included along with the Boraflex sites since this notice L
may be of greater interest to the licensee's who have a similar fuel rack system to that of Quad Cities.
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'The BISCO program was rewritten to summarize the intent'of in-progress tests which are being conducted with the assis -
tance of outside consultants.
The design of a special test method to measure gaps was not part of BISCO's program,.and BISCO does not dispute the actual measurements reported, but does dispute the conclusions of the NETCO report where
" worst case" assumptions were made in the absence of data'now evolving from the current test programs.
i The EPRI program was also rewritten from specific task de -
l scriptions in the EPRI project guidelines paper, and the wording of the rewritten paragraph was verbally presented to Mr. Ray Lambert of EPRI for his concurrence on accuracy The reference to isotropic / anisotropic behavior was deleted since it is purely speculative and is unimportant in the presence of actual test data now available.
The reference to radiation damage mechanisms was also deleted because it-is speculative and the interpretation of d
" damage" is primarily a function of intended use.
- Again, f
actual test data defining shrinkage and stability is now t
avnilable decreasing the need to forecast performance on the I
basis of mechanism theory.
Although stress, temperature, and chemical environment impact Doraflex, it is the interactive effect of the rack and 1
handling on the stressed or exposed Boraflex that governs primary performance, therefore, the concept of " system" is again, introduced.
i The goal of improving industry understanding is clarified
.)
to reflect the study of all aspects related to the observed gaps at Quad Cities, and to determine whether there are com-mon elements which should be evaluated elsewhere.
We are not aware of a general condition of degradation of Boraflex as l
implied in the first draft.
I hope the comments and background reasoning behind our rewritten draft is clear.
We would welcome the opportunity to discuss further with you any of the points raised.
Sincerely, 4 R; -~
- 1. S. Anderson l
President BISCO PRODUCTS, INC.
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. PRELIMINAWNOTIFICATION OF, EVENTOR UNUSUAL OCCURRENCE--PNO-III-82-112 'D:ts: October -18,1982
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Dis, pr51 Adnery n:tificatien csnstitutss EARLY notico ef svants of POSSIBLE safety sr '
ipublia tnurtst' significance. The information 1s as' initially'receivsd without vari--
"*?* etic /f or' evaluation,; and'is basically;all' that isjknown by. the staf f on this' date.
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dC ility: 1 Commonwealth Edison Company Lice:Me Emergency Classification:
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l Quad Cities Nuclear Plant L.)1 notification of. Unusual Event
(%),
Alert Units 1and-2 Site Area Emergency
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q Docket Nos.
50-254 50-265 General Emergency y
n_,,Not Applicable
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'Subj2ct:L BOWED' SPENT FUEL STORAGE RACKS-The licensee informed Region III (Chicago) that three high density fuel storage i
-racks installed at the Quad Cities Station do not meet the design criteria for spacing between the installed racks because of a bowing condition. The. separation criteria, intended to. prevent' contact beteen the racks during a seismic event,.
rsquire a 3-incE separation.,The bowing condition has reduced the'stparation to
'.cbout 2-1/2 inches.
Joseph'00ts_Corpration,' manufacturer'of the. racks / haty teenalyzed the seismic response of the racks end concluded that a 2-1/2 separation is"acceptdle for fully r
Loaded racks and partially loaded (racks with a symetrical distribution'of the fuel assemblies./
3 one rack 'at Quad Cities is'fulty/ loaded; n'second is partially loaded and the fuel has been rearranged in a symet!ical array; and the third is e'mpty.
6 N
.) y R gion. III is considering(the generic potential of the bowins ccoditica.
Joseph Octs
- crporation has supplied' storage racks to at least two other aites - Point Beach and
'Oconee. The Point Beach resident inspector and the Repon M MAtlanta) office have.
baen notified. The Office of Nuclear Reactor Regulation hos olso been advised of the
-Quad Cities rack bowing.
i Naither Region III nor the licensee plans to issue a news ar.nouncement.
'The State of Illinois will be advised.
Region III was notified of the bowing ~ condition on October 15, 1982.
Subsequent
'infor fion'was obtoined on October 18. -This information is current as of 2:30 p.m.
(CDT),"Detober 18,"1982.
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Contact:
. Grobe R. Walker J. Streeter 384-2520 384-2565 384-2541 DISTRIBUTION:
L St., N'$b..
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PDR RegionsI;73.3,II GA, IV PJD, V 94 f Licensee (Corporate Offica) @
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Rev. 5/28/82 g